Roller tappet guard

ABSTRACT

In a multicylinder device, such as a fuel injection pump, between two adjacent roller tappets there is fixedly held in the pump housing a securing pin which, by virtue of parts thereof cooperating with parts of said roller tappets, prevents the latter from turning and the roller pins from axially sliding.

Unite States aient 1151 3,668,945 Hoimann 1 June 13, 1972 ROLLER TAPPETGUARD [56] References Cited [72] Inventor: Eberhard Hofmann, Neuhof,Germany UNITED STATES PATENTS 73 Assignee; Robe" Bosch GmbH, Stuttgart,Germany 1,061,700 5/1913 Steinbecker ..74/569 2,935,878 5/1960 Wirsching..l23/90.5 Flledz M h 3, 9 3,139,076 6/1964 Flaherty ..123/90.5 [21]Appl 12165- Primary ExaminerWi1liam F. O'Dea Assistant Examiner-F. D.Shoemaker [30] Foreign Application Priority Data Attorney-Edwin E.Greigg March 18, 1969 Germany ..P l9 13 519.4 57 ABSTRACT 52 us. c1...74/569, 123/905, 417/539 In multicylinder device, such as a fuelinjection p 51 1 1111. C1 ..Fl6h 53/06 between two adjacent PR isfixedly held in the 581 Field of Search ..74/569; 123/905; 417/539 Pumpmusing securing Whlchl by virtue Pirts there cooperating with parts ofsaid roller tappets, prevents the latter from turning and the rollerpins from axially sliding.

2 Claims, 6 Drawing Figures ROLLER TAPPET GUARD BACKGROUND OF THEINVENTION This invention relates to guard means which, in multicylinderpump structures, particular multicylinder fuel injection pumps, preventsthe roller tappets from turning about their axes during operation.conventionally, two immediately adjacent tappets are flattened on facingsides and are secured against rotation by means of a pin inserted intothe pump housing and extending in a direction perpendicular to thetappet axis.

In known structures of the aforenoted type (such as disclosed in GermanPat. No. 1,016,497 and U.S. Pat. No. 2,410,947), the rotatably orfixedly inserted pin serves merely to prevent the roller tappet fromrotation. In such structures the roller pin of the tappet has to besecured against axial displacement by additional means such as forcedfitting, rivetting, the provision of cotter pins, or the like.

In other known fuel injection pumps, two adjacent tappets and rollerpins are secured against undesired displacement by means of T-shapedplates inserted perpendicularly to the tappet axis and longitudinallywith respect to the pump. It is a disadvantage of such structures thatsaid plates are difficult to install and further, grooves have to beprovided in the housing walls. .Such grooves weaken the housing andrequire an involved machining operation.

OBJECT AND SUMMARY OF THE INVENTION It is an object of the invention toprovide an improved guard or securing means of the aforenoted typewhich, in addition to securing the roller tappets against rotation,secures the roller pins against axial displacement or rotation withoutappreciably weakening the pump housing.

Briefly stated, according to the invention there is provided a pininserted in the pump housing between two adjacent roller tappets; saidpin is provided with two diametrically opposed parallel flattenedportions associated with the flattened portions of the tappet, saidflattened portions on the securing pin also serve for preventing anaxial displacement of the roller pin carrier by each tappet.

The invention will be better understood, as well as further objects andadvantages become more apparent, from the ensuing detailed specificationof two exemplary embodiments taken in conjunction with the drawing.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a fragmentary axial sectionalview of a multicylinder serial fuel injection pump incorporating a firstembodiment of the invention;

FIG. 2 is a sectional view along line II-II of FIG. 1;

FIG. 3 is a perspective'view of a securing pin incorporated in thestructure shown in FIGS. 1 and 2;

FIG. 4 is a fragmentary axial sectional view of a multicylinder serialfuel injection pump incorporating a second embodiment of the invention;7

FIG. 5 is a section view along line V-V of FIG. 4; and

FIG. 6 is a perspective view of a securing pin incorporated in thestructure shown in FIGS. 4 and 5.

DESCRIPTION OF THE EMBODIMENTS In the description that follows, similaror identical components in the two embodiments are designated by thesame reference numeral, differentiated by a prime sign.

In both embodiments, in an only partially shown housing 1, 1' of thefuel injection pump, there is rotatably held a cam shaft 2, 2, the cams3, 3' of which are engaged by at least two adjacent roller tappets 6, 6'provided with flattened portions 4, 4 and guided in housing bores 5, 5'.To each tappet 6, 6' there is secured a roller 8, 8' by means of aroller pin 7, 7'. The rollers 8, 8' are urged into contact with the workface of cam 3, 3' by means of a tappet spring 9, 9' supported in thehousing 1, 1 The tappet spring 9, 9' exerts its force on the tappet 6,6'

through a spring seat disc 10, 10' disposed in a cavity 64, 6a of tappet6, 6'. The spring seat disc l0, 10 is provided with a central openingthrough which extends a terminal portion of piston l2, l2. Said terminalportion carries an integral collar 11, 11 which is held captive with asmall clearance between spring seat disc 10, 10' and the base l3, 13 ofthe respective cavity 6a, 6a.

Into the housing 1, 1' there is force-fitted, between two tappets 6, 6'a securing pin 14, 14 disposed perpendicularly to both the axes of thetwo adjacent tappets 6, 6 and those of roller pins 7, 7. Each securingpin 14,14 has two cylindrical terminal portions 14a, 14a, and 14b, 14band a mid-portion which has two diametrically opposed flattened parts15, 15', extending normal to the axis of each roller pin. The faces l5,l5, cooperating with the flattened tappet portions 4, 4', prevent thetappets 6, 6 from rotating. At the same time, the planar faces 15, 15'are at least of such an area that the ends l6, 16 of the roller pins 7,7' do not slide beyond the outline of said area during the strokes ofthe tappets 6, 6'. Stated in different terms, if the peripheral outlineof a roller pin is orthogonally projected onto the immediately adjacentplanar face of the securing pin at any momentary position of theassociated tappet during its reciprocation, at least one part of suchprojection intersects the last-named planar face of the securing pin.This arrangement may be well observed in FIG. 1 in which the two tappetsare shown in opposite extreme positions. Or, it may also be said that asit may be well observed in FIG. 1 the planar faces of the securing pinlie in a plane that is parallel to the direction of reciprocation of thetappets and the dimension C of each planar face taken in the directionof reciprocation is at least as large as the amplitude B (indicated inFIG. 1 as the distance between the axes A of two adjacent roller pinsdepicted, as mentioned earlier, in the two opposite extreme positions).Furthermore, as it also may be observed in FIG. 1, each planar face ofthe securing pin is so arranged with respect to the adjacentreciprocating roller pin that the axis A of the latter, in both extremepositions of the roller pin and in any positions therebetween, passesthrough a point that is located on the adjacent planar face of thesecuring pin. The other ends l7, 17 of roller pins 7, 7 glide along thewall of the housing bore 5, 5'. In this manner, the roller pins 7, 7'are prevented from displacement in either axial direction.

The frontal faces 16, 16' and 17, 17' are rounded in order to improvetheir gliding properties. The securing pin 14, 14' has at the frontalface of the cylindrical terminal portion 14b, 14b a slot 22, 22', theedges of which extend parallel to the faces 15, 15', thus permitting anaccurate positioning during the force-fitting thereof into the pumphousing 1, l

In the second embodiment for securing the tappets in a multicylinderfuel injection pump (FIGS. 4, 5), preferably of the V-configuration, theroller tappets 6' have lower terminal portions 18 of reduced diameter toprevent an engagement of the roller tappets 6' of one pump series with acam 3" of the cam shaft 2 associated with the other pump series. For thesame purpose, the roller pins 7' have a notched or cut-out lower portion7a.

In order to prevent rotation of the roller pins 7' during operation,they are provided with integral stubs 19 which glide in grooves 20provided in the securing pin 14' and extend parallel with the tappetaxis. The securing pin 14' has in its mid-portion a planar face 21confronting the cam 3" to permit a free passage thereof.

The embodiment described in connection with FIGS. 4-6 is particularlyadvantageous since it permits a substantial reduction of the overalldimensions of a V-type pump.

That which is claimed is:

1. In a guard means for tappets operating in a multicylinder fuelinjection pump, said tappets are of the reciprocating type that carry aroller mounted by a roller pin, said guard means is of the known typethat includes a securing pin fixedly held in the housing of saidmulticylinder device between two adjacent tappets, said securing pincooperates with flattened areas of said tappets to prevent rotation ofthe latter, the improvement comprising, two diametrically opposed planarface portions provided in said securing pin, each said planar faceportion extending parallel to and cooperating with a flattened area ofsaid two adjacent tappets, said planar face portions of said securingpin being disposed immediately adjacent a terminus of each roller pin ofsaid two adjacent tappets, each planar face portion lying in a planedisposed parallel with the direction of reciprocation of said tappets,the dimension of each planar face portion measured parallel with saiddirection of reciprocation being at least as large as the amplitude ofsaid reciprocation, each planar face portion being so disposed withrespect to the adjacent reciprocating roller pin that in both extrememomentary positions of the roller pin and in any momentary positionstherebetween, the axis of said roller pin passes through a point locatedon the adjacent planar face portion of said securing pin.

2. In a guard means for tappets operating in a multicylinder device,particularly a fuel injection pump, said tappets are of thereciprocating type that carry a roller mounted by a roller pin, saidguard means is of the known type that includes a securing pin fixedlyheld in the housing of said multicylinder device between two adjacenttappets, said securing pin cooperates with flattened face portions ofsaid tappets to prevent rotation of the latter, the improvementcomprising, two diametrically opposed planar face portions provided insaid securing pin, each said planar face portion extending parallel toand cooperating with a flattened face portion of said two adjacenttappets, said planar face portions of said securing pin being disposedimmediately adjacent a tenninus of each roller pin of said two adjacenttappets, each said roller pin remaining within the outline of saidplanar face portions at all times during the reciprocation of saidtappets and a groove provided in each planar face portion of saidsecuring pin, each groove extending parallel to the path ofreciprocation of said tappets, each said terminus of said roller pinsincludes an integral lug extending into and guided in the groove of animmediately adjacent planar face portion of said securing pin.

i l l t I!

1. In a guard means for tappets operating in a multicylinder fuelinjection pump, said tappets are of the reciprocating type that carry aroller mounted by a roller pin, said guard means is of the known typethat includes a securing pin fixedly held in the housing of saidmulticylinder device between two adjacent tappets, said securing pincooperates with flattened areas of said tappets to prevent rotation ofthe latter, the improvement comprising, two diametrically opposed planarface portions provided in said securing pin, each said planar faceportion extending parallel to and cooperating with a flattened area ofsaid two adjacent tappets, said planar face portions of said securingpin being disposed immediately adjacent a terminus of each roller pin ofsaid two adjacent tappets, each planar face portion lying in a planedisposed parallel with the direction of reciprocation of said tappets,the dimension of each planar face portion measured parallel with saiddirection of reciprocation being at least as large as the amplitude ofsaid reciprocation, each planar face portion being so disposed withrespect to the adjacent reciprocating roller pin that in both extrememomentary positions of the roller pin and in any momentary positionstherebetween, the axis of said roller pin passes through a point locatedon the adjacent planar face portion of said securing pin.
 2. In a guardmeans for tappets operating in a multicylinder device, particularly afuel injection pump, said tappets are of the reciprocating type thatcarry a roller mounted by a roller pin, said guard means is of the knowntype that includes a securing pin fixedly held in the housing of saidmulticylinder device between two adjacent tappets, said securing pincooperates with flattened face portions of said tappets to preventrotation of the latter, the improvement comprising, two diametricallyopposed planar face portions provided in said securing pin, each saidplanar face portion extending parallel to and cooperating with aflattened face portion of said two adjacent tappets, said planar faceportions of said securing pin being disposed immediately adjacent aterminus of each roller pin of said two adjacent tappets, each saidroller pin remaining within the outline of said planar face portions atall times during the reciprocation of said tappets and a groove providedin each planar face portion of said securing pin, each groove extendingparallel to the path of reciprocation of said tappets, each saidterminus of said roller pins includes an integral lug extending into andguided in the groove of an immediately adjacent planar face portion ofsaid securing pin.